With the continuous improvement of radio technology, a variety of radio services spring in large numbers. There are limited radio-service-bearing spectrum resources, which are in short supply with respect to increasingly higher requirements on the bandwidths. The utilization rate of the spectrum resources is low under a conventional mode of fixed spectrum allocation. In a sense, the spectrum resource shortage is caused by such a spectrum allocating system of fixed allocation to an authorizing system. With Cognitive Radio as a break from the conventional fixed spectrum allocation system, dynamic inter-system spectrum allocation is performed, increasing a spectrum utilization rate. Simple voice data communication can no longer meet a continuously increasing daily communication requirement. A video streaming service has become a continuously increasing share of daily communication. This may require support of a larger bandwidth, such that an International Mobile Telecom (IMT) system shows an unprecedented spectrum shortage. On the other hand, for a Radio and TV system, largely there is spectrum resource space available. For example, some Radio and TV system spectra may not be put to use in some area; some Radio and TV system spectra, although covering some area, are not always put to use, leading to a low overall utilization rate. However, with fixed spectrum allocation, such unused spectrum resources cannot be re-used, such as by the IMT system. With Cognitive Radio, the IMT system may acquire information on the Radio and TV system and wait to take over spectrum resources not used by the Radio and TV system in space and time, thus increasing utilization rate of a spectrum of the Radio and TV system, improving the spectrum shortage in the IMT system. Unused spectrum resources of the Radio and TV system is referred to as a TV White Space (TVWS). A system waiting to take over a spectrum authorized to be used by another system may be referred to as a secondary system or a secondary user. A system authorized to use the spectrum may be referred to as a primary system or a primary user. Therefore, in the aforementioned scene, the Radio and TV system is a primary system, and the IMT system is a secondary system.
Network architecture of an actual Cognitive Radio system may contain three layers, namely a database (DB), a reconfiguration managing node such as a Central Control Point (CCP), and a secondary user equipment. The secondary user equipment may be a Base Station (BS), an accessing node under management, a terminal, or the like. As shown in FIG. 1, one or more reconfiguration managing nodes respectively access the database, and respectively manage secondary user equipment under respective management. The secondary system 1 may consist of the CCP1, BS1, BS2, BS3, and any terminal under management of any BS. Spectrum resource utilization may be managed by the CCP1. Multiple secondary user equipment working on a same TVWS spectrum resource produce overlapping interferences to the primary user, as shown in FIG. 2. When Cognitive Radio BSs a, b, and c simultaneously use a TVWS spectrum resource f1, a primary user A authorized to use the same frequency domain f1 will endure a superposition of interferences produced by the BSs a, b, and c. A superposition of interferences produced by the BSs a, b, and c will not impact the normal functioning of the primary user A only if it is less than an interference threshold of the primary user A. In this case, it is not enough to consider only a single secondary user equipment. A maximal transmit power for a single secondary user, computed according to a locational relation between the primary user and just the single secondary user, a propagation model, and an interference tolerance of the primary user, will be meaningless. Instead, the transmit power for the BSs a, b, c may have to be computed. It is known that a database computes the transmit power for any user equipment under management, while a reconfiguration managing node plays no role in such computation. Thus, any secondary user equipment may share the interference tolerance of the primary user. The database is configured for storing primary user spectrum resource usage information, managed by an operator of a primary system or an operator of a third party. The database may be a geo-location database.
Such management by a single node, such as when the transmit power of any secondary user equipment is computed by the database, may lead to a problem, specifically as follows.
1, it is not adapted to flexible power control among secondary system equipment. The database as a global managing node manages all secondary user equipment. Each time a secondary user equipment is added on a TVWS spectrum resource, the database may be triggered to perform TVWS spectrum resource allocation, and even transmit parameter re-adjustment for equipment in multiple secondary systems. This will impact system stability.
2, a delay may be uncontrollable. A processing delay, of the database as an entity operated by the operator of the primary system or a third party, is not controlled by a secondary system. Therefore, the overall reconfiguration process can hardly meet a service continuity requirement of a secondary system.